This invention relates generally to cathode ray tubes and more particularly to tension mask support frame assemblies having a vibration damping scrubber on a support blade member which holds a tension mask.
A color cathode ray tube, or CRT, includes an electron gun for forming and directing three electron beams to a screen of the tube. The screen is located on the inner surface of the faceplate panel of the tube and is made up of an array of elements of three different color-emitting phosphors. A shadow mask, which may be either a formed mask or a tension mask having strands, is located between the electron gun and the screen. The electron beams emitted from the electron gun pass through apertures in the shadow mask and strike the screen causing the phosphors to emit light so that an image is displayed on the viewing surface of the faceplate panel.
One type of CRT has a tension mask comprising a set of strands that are tensioned onto a mask support frame to reduce their propensity to vibrate at large amplitudes under external excitation. Such vibrations would cause gross electron beam misregister on the screen and would result in objectionable image anomalies to the viewer of the CRT.
One method of tensioning a mask utilizes a mask support frame having a pair of support blade members mounted on opposite sides of the frame parallel to the major axis of the CRT. The tension mask extends between the support blade members and is held in tension to reduce it""s propensity to vibrate. A problem exists in that the support blade members supporting the mask are subject to vibration relative to the frame when external vibration is applied to the frame. Such external vibrations are then transferred to the tension mask.
The invention provides a tension mask support frame assembly for a CRT having a pair of support blade members attached to a frame. The support blade members are attached to opposite sides of the frame at a central location whereby each support blade member has a pair of distal ends extending from the central attachment point. A damping scrubber is disposed in the space between the support blade member and the frame near the support blade members"" distal end. Vibrations in the support blade members are thereby reduced through rubbing action of the damping scrubbers against the frame. The fundamental frequency of vibration of the support blade member is also increased by having the distal ends of the blades touching the subframe.